Plaque is recognized as a precursor of such oral diseases as caries and gingivitis. The gums of the mouth of humans and lower animals may be harmed by deposits of dental plaque, a combination of minerals and bacteria found in the mouth. The bacteria associated with plaque can secrete enzymes and endotoxins which can irritate the gums and cause an inflammatory gingivitis. As the gums become increasingly irritated by this process they have a tendency to bleed, lose their toughness and resiliency, and separate from the teeth, leaving periodontal pockets in which debris, secretions, more bacteria and toxins further accumulate. It is also possible for food to accumulate in these pockets, thereby providing nourishment for increased growth of bacteria and production of endotoxins and destructive enzymes. This can result in destruction of bone and gum tissue.
With such problems being possible from plaque/gingivitis it is not surprising that extensive efforts have been expended in trying to find effective treatment compositions. Many of these efforts have used quaternary ammonium compounds or bis-biquanides such as chlorhexidine which is used in Peridex.RTM. sold by The Procter & Gamble Company.
Another material which has been considered is stannous ion. Such a material is disclosed in Svatun B., "Plaque Inhibiting Effect of Dentifrices Containing Stannous Fluoride", Acta Odontol. Scand., 36, 205-210 (1978); and Bay I., and Rolla, G., "Plaque Inhibition and Improved Gingival Condition By Use of a Stannous Fluoride Toothpaste", Scand. J. Dent. Res. 88, 313-315 (1980).
In spite of the many disclosures in the antiplaque/antigingivitis area, the need for improved products still exists. In U.S. Pat. No. 5,004,597, Apr. 2, 1991, to Majeti et al., oral compositions are described containing stannous fluoride stabilized with stannous gluconate. These compositions provide excellent antiplaque and antigingivitis benefits. However the compositions do cause some staining of enamel surfaces.
The present inventors have discovered that the staining can be reduced by the use of a composition containing pyrophosphate ions with the stannous ion formulation.
It is an object of the present invention therefore to provide compositions which deliver an improved antiplaque/antigingivitis benefit with reduced staining.
It is a further object of the present invention to provide improved products utilizing stannous fluoride and another stannous compound in one composition and pyrophosphate ions in another.
It is still a further object of the present invention to provide an effective method for treating plaque/gingivitis with the above described compositions.
These and other objects will become clearer from the detailed description which follows.
All percentages and ratios used herein are by weight of the total compositions unless otherwise specified. Additionally, all measurements are made at 25.degree. C. in the composition or in an aqueous solution/dispersion unless otherwise specified.